port js files in lib and lib/containers to ts (#3957)

* rename files in lib and lib/containers to ts

* add types

* fix ts errors

lib/selectors.ts

@@ -0,0 +1,13 @@
+import {createSelector} from 'reselect';
+import {HyperState} from './hyper';
+
+const getTermGroups = ({termGroups}: Pick<HyperState, 'termGroups'>) => termGroups.termGroups;
+const getRootGroups = createSelector(
+  getTermGroups,
+  termGroups =>
+    Object.keys(termGroups)
+      .map(uid => termGroups[uid])
+      .filter(({parentUid}) => !parentUid)
+);
+
+export default getRootGroups;